海洋深水钻井油基钻井液气体溶解度计算

GAS SOLUBILITY CALCULATION IN OIL BASED DRILLING FLUID DURING DEEPWATER DRILLING

在深水钻井过程中,泥线上、下井筒温度差异较大,受温度、压力的影响,气体会溶解于钻井液中,也会从钻井液中逸出,气体在环空中存在的状态对环空压力的影响较大。为此,以天然气在水和油中的溶解度计算模型为基础,建立了气体在水基钻井液和油基钻井液中的溶解度计算理论模型,分析了深水环境下气体在水基钻井液和油基钻井液中的溶解度随温度、压力的变化。计算结果表明,随着压力的增加,气体在水基和油基钻井液中的溶解度随之增加; 随着温度的增加,气体在水基和油基钻井液中的溶解度减小。在相同条件下,油基钻井液气体溶解度远大于水基钻井液气体溶解度。

During deepwater drilling,the wellbore temperature distinction is quite obvious in comparison with that above and below the mud line.Due to wellbore temperature and pressure variation,the gas will dissolve in or escape from the drillingfluid,such state of gas has great influence on the annulus pressure.For this reason,based on the model of natural gas solubility calculation in water and oil,the theoretical calculation models of gas solubility in oil-based and water-based drilling fluid were established,which managed to analyze the change of gas solubility in the water-based and oil-based drilling fluid according to temperature and pressure variation.The results showed that:the gas solubility increased with pressure increase,but gas solubility decreases with the temperature increasing.While given the same pressure and temperature,the gas solubility in oil-based drilling fluid was much greater than that in water-based drilling fluid.